Team Calendars reminder email contains links to broken page, cannot Turn off reminders

Summary

The links in Team Calendars reminders emails point to a broken page. This applies to both links. One to direct to the calendar event and the other to "Turn off reminder".  The links direct to a page that contains a spinner, unformatted text, and buttons that don't work.  It's unclear what the page was supposed to do.

Environment

• Confluence 6.2.3
• Team Calendars 5.3.19

Steps to Reproduce

Environment setup

1. In Confluence, add a valid mail server so that calendar event reminders and notifications can be emailed
2. Install Team Calendars Add-on
3. Create a Team Calendar

Steps to reproduce issue

1. Create a team calendar event
2. Add a user to the event in Who
3. Add a reminder 5 minutes before
4. Hit OK to save the event (save this with enough time before the event reminder should be sent)
5. Wait for the reminder email to be sent out
6. When the Team Calendars Reminders email is received
7. Try both links:
   • Turn off reminders
   • Link to the calendar event (event name)
   • The link will direct to a page that.... looks all kinds of broken and not functional

Expected Results

The links in the reminder email should take the user to the respective pages to view the event and/or turn off the reminders

Actual Results

See screenshot for the page the links direct to. The page is not functional. The spinner keeps spinning. The buttons don't work.

Workaround

The user can login and navigate to the event manually to view the event details but they can't "turn off reminders".
This documentation says there should be a "Stop reminding me" link in the email, but that doesn't exist.
See: https://confluence.atlassian.com/teamcal/reminders-693899708.html ("You can also opt-out of reminder emails for an event type by clicking the 'Stop reminding me' link in the reminder email.")